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Can Your Microbiome Reveal Your Ideal Diet?

Forget carbs and calories. Your microbiome may hold the key to better blood sugar control, and a $500 analysis may reveal your ideal diet.

By
Monica Reinagel, MS, LD/N, CNS
Episode #551
healthy carbs
The Quick And Dirty

Traditional guidelines for controlling blood sugar focus on the composition of the foods. Now, scientists have developed an algorithm that predicts your response to foods based on the composition of your gut.

A personalized diet based on your gut microbiome may be more effective in controlling blood sugar than counting carbs. 

If you are concerned about high blood sugar and have $500 to spend, Day Two’s microbiome analysis might be a good investment in your health.

For those with diabetes or prediabetes, managing blood sugar levels is a critically important part of preventing the progression of this disease and avoiding serious complications. But even for healthy people, keeping your blood sugar in a healthy range can help reduce the risk of obesity and the risk of developing diabetes.

How do you avoid high blood sugar?

Up until recently, advice for managing your blood sugar has focused on the nutritional composition of foods. Specifically, you’re advised to pay attention to the quantity and quality of carbohydrates in your diet.

Two different foods with the same amount of carbohydrate or sugar or fiber can still produce very different glycemic responses.

Tracking quantity is pretty straight-forward: you simply count grams of carbohydrates. Assessing the quality of the carbohydrates in your diet gets a little more nuanced. You might take into account how much sugar or fiber a food contains, for example.

The problem is that two different foods with the same amount of carbohydrate or sugar or fiber can still produce very different glycemic responses. A white potato, for example, might have the same amount of carbohydrate and fiber as a serving of white pasta. But the potato is likely to cause a higher spike in blood sugar.

Is Glycemic Index more important than carbs?

This was the problem that the glycemic index hoped to solve, by attempting to factor in the variable known as the human digestive process. Researchers fed human volunteers all kinds of different foods and measured their blood sugar levels. They used this data to produce the Glycemic Index, which represents the average rise in blood sugar in response to various foods. As a final step, multiplying the Glycemic Index of a food by the amount of carbohydrate in the serving gives you the Glycemic Load, which is a measure of both quality and quantity.

The Glycemic Index of a food might be 58, but the range of individual responses included in that average might be 47 to 69.

For decades now, our best tools for managing blood sugar have been counting carbs or glycemic load. And studies have shown both to be moderately effective in controlling blood sugar and improving outcomes in people with or at risk of diabetes.

But there was still a big problem. The Glycemic Index of a food represents the average blood response to that food among all the individuals tested. But If you dig into the data, you’ll see that those averages represent a very wide range of individual responses. The Glycemic Index of a food might be 58, but the range of individual responses included in that average might be 47 to 69.

Why does the same diet work not work for everyone?

You see the problem. Not only can foods with a similar amount of carbohydrate produce wildly different blood sugar responses. But the identical food can produce wildly different blood sugar responses in different individuals. Trying to control your blood sugar by counting carbs or even counting glycemic load is a little like trying to buy the perfect house based only on price and zip code. You might get lucky and end up in your dream home, but there’s an awful lot of room for error.

The billions of bacteria that reside in our intestines have a surprisingly big say about what goes on in our bodies—including our glycemic response to food.

Why is there so much variation in our individual responses to foods? Part of the answer appears to reside in the gut. The billions of bacteria that reside in our intestines have a surprisingly big say about what goes on in our bodies—including our glycemic response to food. And scientists have now found that knowing the makeup of your intestinal bacteria can help you predict your individual blood sugar response to foods.

Can your microbiome reveal your ideal diet?

Researchers from the Weizmann Institute in Israel analyzed the gut microbiome of 800 people. They also hooked these folks up to continuous blood glucose monitors and tracked everything they ate. In addition, they collected blood samples and other information about the subjects' health history, sleep, and exercise habits. They then loaded all of this data into a computer and used artificial intelligence to develop an algorithm that predicts an individual’s response to foods.

People following a personalized dietary prescription generated by the algorithm had more success controlling their blood sugar than others who were simply counting carbs.

The next step was a double-blind study in which half the people followed a dietary prescription generated by the algorithm and the other half followed standard the carbohydrate counting method recommended by the American Diabetes Association. They found that people following a personalized dietary prescription generated by the algorithm had more success controlling their blood sugar than others who were simply counting carbs. These results were then reproduced in a second study conducted by the Mayo Clinic.

This technology has now been licensed by a commercial company called Day Two and for $500 you can get an analysis of your microbiome (spoiler alert: there’s poop involved). Based on your analysis, they will provide personalized dietary advice for managing your blood sugar. Using their app or website, you can look up virtually any food or combination of foods and get a score that predicts your blood sugar response.

This is definitely an important step toward improving healthcare by providing more personalized recommendations. But there are still a few gaps in the research.

Day Two promotes this test primarily to diabetics and their doctors. So far, however, the only published results are from studies using healthy individuals. But, in addition to the controlled studies, the company has collected and analyzed data from thousands of users, including diabetics. The results reported by their users, while not publishable as research data, nonetheless suggest that the approach is effective for people with diabetes. Controlled studies involving prediabetic and diabetic subjects are apparently underway with results due to be published later this year.

The Bottom Line

If you are concerned about your blood sugar, start by paying attention to the quantity and quality of carbohydrates in your diet. (Here’s more on that.) Losing weight is also a sure-fire way to improve glucose control, which is why paying attention to calories can also help. But if you’ve found that these more conventional approaches are not working and you have $500 to invest, I think there’s enough science here to justify an n-of-1 experiment.

Keep in mind that changes in your diet (or your blood glucose levels) are likely to result in changes in your microbiome. For this reason, the company suggests retesting yearly to get updated recommendations.

A final note of caution: There are several companies selling personalized diets based on analysis of your gut microbiome or DNA. They don’t all have the same level of scientific validity to back up their claims or methodology. My qualified recommendation of Day Two does not necessarily extend to other similar products or services.

I have no doubt that this science and the technology will continue to evolve. And I’ll keep you up to date with those developments as they happen!

About the Author

Monica Reinagel, MS, LD/N, CNS

Monica Reinagel is a board-certified licensed nutritionist, author, and the creator of one of iTunes' most highly ranked health and fitness podcasts. Her advice is regularly featured on the TODAY show, Dr. Oz, NPR, and in the nation's leading newspapers, magazines, and websites. Do you have a nutrition question? Call the Nutrition Diva listener line at 443-961-6206. Your question could be featured on the show. 

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